Carbon Monoxide Hazards Toolbox Talk

Carbon monoxide is a serious jobsite hazard because you cannot see it, smell it, or taste it. It can build up fast when crews use gas, diesel, propane, or other fuel-powered equipment in enclosed or partly enclosed spaces. Generators, heaters, saws, compressors, power washers, forklifts, and vehicles can all create dangerous levels, especially in basements, garages, shafts, tunnels, and buildings with limited airflow.

This talk covers where carbon monoxide exposure happens, the warning signs crews need to know, and the steps needed to prevent workers from getting sick. The focus is on controlling exhaust, using the right equipment in the right place, watching conditions as the job changes, and knowing when work must stop immediately.

Why This Matters

• Carbon monoxide can overcome workers without warning because it has no smell or visible cloud.
• Exposure can cause headache, dizziness, nausea, confusion, and loss of consciousness.
• High levels can build up quickly in enclosed areas even during short tasks.
• Symptoms can be mistaken for fatigue, heat stress, or illness, which delays action.
• One machine running near an opening can still push exhaust back inside if airflow changes.

Common Hazards

• Running generators, heaters, or compressors inside buildings, basements, or parking structures.
• Using fuel-powered saws, lifts, pressure washers, or other equipment in areas with poor ventilation.
• Leaving trucks, vans, or forklifts idling near doors, air intakes, or partially enclosed work zones.
• Using temporary heat during cold weather without checking how exhaust is vented.
• Working in tunnels, pits, shafts, crawlspaces, or other low-airflow areas where gas can build up.
• Wind shifts, closed doors, or plastic sheeting changing airflow and trapping exhaust where crews are working.

Safety Checklist

Before Work Begins

• Identify all fuel-burning equipment that will be used on the job.
• Choose electric or battery-powered tools when possible for indoor or enclosed work.
• Check where exhaust will go before starting any generator, heater, vehicle, or engine-driven tool.
• Make sure ventilation is adequate for the space and the equipment being used.
• Inspect equipment for damaged exhaust systems, poor maintenance, or other signs it is not running clean.
• Confirm carbon monoxide monitoring is available where needed and workers know the exposure signs.

During Work

• Keep fuel-powered equipment out of enclosed spaces unless it is specifically approved and properly controlled.
• Position exhaust away from workers, entrances, air intakes, and other occupied areas.
• Watch for symptoms like headache, dizziness, nausea, weakness, or confusion.
• Do not assume an open door or cracked window is enough ventilation for engine exhaust.
• Recheck conditions if doors close, fans stop, weather changes, or the work area is enclosed with tarps or plastic.
• Shut equipment down right away if workers report symptoms or monitoring shows unsafe conditions.

Crew Talking Points

• What fuel-powered equipment are we using today, and where will it operate?
• Which areas on this site could trap exhaust or have poor airflow?
• Are there better electric or battery-powered options for this task?
• What symptoms should every worker watch for in themselves and others?
• How will we keep exhaust away from doors, intakes, and nearby crews?
• Speak up now if ventilation is weak, equipment is running rough, or you are unsure whether a space is safe for engine-driven tools.

Stop Work If

• A fuel-powered machine is being used in an enclosed or poorly ventilated area without proper controls.
• Any worker shows signs of carbon monoxide exposure, including headache, dizziness, nausea, or confusion.
• Exhaust is entering the work area, break area, or building through openings or air intakes.
• Ventilation fans fail, doors close, or site conditions change and trap exhaust.
• Carbon monoxide monitoring alarms or indicates unsafe levels.
• Equipment has a damaged exhaust system or is running in a way that suggests a mechanical problem.

Final Reminder

Carbon monoxide gives no warning before it hurts people. Keep exhaust out of the work area, watch the crew for symptoms, and stop work the moment conditions are no longer safe.